Syritis

iTrader: (2)

I got my engine together, i've put almost 500km on it and it was bogging and i had no power untill 1500rpm. My boost gauge was running at 3in.hg vaccum at idle and it would boost with any throttle play, even with no load. but on decel it would go upto 20-25 in.hg vacuum. it would run really rich untill 2000rpm.
Now after a week of trouble shooting My car will almost start but not quite. I've gone over a few things and still have no clue.
- Not Vacuum leak, (tested with Carb cleaner and Brake kleen)
- Not Ignition coils and wires (in the middle of testing plugs)
- Not BOV (temp. eliminated)
- Not BAC (temp. eliminated)
- Not TPS (replaced and adjusted to Exactly 1ohm)
- Not AFM (all resistances are good)
- Not map sensor (Replaced)
- Not ACV (Eliminated)

So the only thing i have left to Test is the plugs, fuel pump and ECU. and then i've tryed everything.
Does anyone know what i can do, i've talked with 2 other people with this problem and noone has any ideas.

Chris Ng

Okay.. because it's expected from me.. I must be a dink...

Don't you work for rx-7 specialties?Isn't adam giving you a hand with this motor? did he build this motor for you?

okay okay.. I'll try and be more helpful..

If you've ruled out an vac leaks, and you're only pulling 3in vac at idle, the only other things that could cause that (ruling out a bad motor, incorrect vac source for the gauge) would be a very rich condition ..

what injectors are you running? have you checked the impedence of them? how about your fuel pump?

just some ideas to throw in your direction..

Have you checked ignition timing?
Have you checked to make sure the FPR on yoru secondary rail has a vacume signal to it? and that the diaphram isn't broken on it?

Syritis

iTrader: (2)

Yes i was expectign adam to come up and, I built the engine myself at the shop. adam has been giving me advise but they're is only soo much he can say when he doesn't have a car too look at. My car isn't at the sho[ b/c me and adam are the only one they're and have been so caught up in work that both of out cars have been negglected.

ANYHOW

I'm paranoid of a blown engine so i have checked the compression a few times. it sounds good but i'll put on a tester tomarrow, even if it is just a piston tester.
i've got the gauge conencted to the vacuum nipple on the lowest part of the upper intake manifold between the rear secondary and primary intake runs.
I've got new (winith 6 months and 10000kms) 550cc primaries. 680cc secondaries aswell as a 3rd gen fuel pump. tomarrow i'll be buying a fuel preassure tester and i'll be testing the pump and FPR.
The timing i did have a hard time to get at TDC, but it's right. I removed the FPD and replaced it with a banjo bolt, but it's been running since then. as well with the FPR, with and without the vacuum line.

Syritis

iTrader: (2)

I checked plug spark and they're all really strong (seen and felt it)
I'm getting 40psi of fuel preassure, I thought it might be dropping off a little fast, so i pulled the intercooler and UIM, pulled the fuel rails and checked for leaks while cranking over the engine. No leaks. Great spray and the ****** thing started, of course I yelled to stop the engine right away. but i'm guessing it's was just from all the gas already inside the chambers.

I'm really out of idea's

Dragoon

Check for vaccum leaks more. Check between intake/block gaskets, as well as injector insulators. Maybe those crazy ports on your motor are causeing shitty vaccum, sort of like a bridgeport. install a proper vaccum guage on it to double check.. you can borrow mine just give me a call

RXciting

Don't wanna jack this thread, but i seem to be having the same problem.

I'm pulling a bit more vacuun then Syritis, but still very little vacuum, only 10 - 15 in. hg.

Compression is about 90psi on all faces. Car is very hard to start when warm and was hard to get the car to idle.

I pulled all the intake manifolds appart yesterday, replaced all vacuum caps, ziptied everything checked injectors, all gaskets and put fresh gasket maker on anything I thought might be causing a problem. Also checked all vacuum hoses for splits or any leaks (used handpump to apply pressure as well as vacuum to 10 in.hg and all was still the same after several minuts.

Also eliminated very large exhaust leak between manifold and engine (2 bottom studs had seen better days and it was impossible to tighten the manifold, 1 nut was 1" front even touching the manifold) Not sure if that might cause a problem with the probably still very little amount of overlap i have just figured i throw all details in.

Car started much easier then before cold, didn't have time to let the car warm up or take it for a drive to test everything. However before it would start and i'd have to give the car gas so it wouldn't stall, not it starts and holds steady solid idle and responds better to throttle.

Thought this might help the thread as well as give a few more ideas as what could be wrong. Any more ideas?


Just another thought I might be running very rich. Due to previouse exhaust leaks etc. I noticed Cheers mentioned a very rich condition, not sure if you meant that only being a problem on startup and idle or also causing a low vacuum reading?

Hope this helps out the original poster somehow!

Syritis

iTrader: (2)

When i pulled my injectors to check for good sprey, i checked the insulators aswell. I've gone over every possible, gasket, even went so far as to pull apart my TB from the UIM ant and re-silicon everything.
I've got 70psi from a normal compression gauge with the shrader valve removed.
I elimanated the compressor side of the turbo and attached the MAF right too my intercooler and it did start 5 or 6 revolutions then stalls. while the intake was off the turbo i check the turbine play again. there is a little freeplay but it's not excessive.
The only idea i have left is the plugs. Right after the rebuild i wasn't 100% sure if my OMP was workign so i put in some cheap premix, then replaced the OMP half a tank later. so i'm thinking that maybe there is enuff oil in the chambers to foul my plus. when was doing the compression test. I checked the plugs and they are a little carbed, and REALLY smell like gas but they're is quite a bit of oil on them aswell. so i'm just going to replaces them, which i have seen work before. but after that. I'm right out of idea's

Dragoon

Maybe your porting is too extreme for good vaccum?

Maxthe7man

On a streetport?... I doubt it, even my bridge engine pulls more than that...

RXciting

well sealing everything up and getting rid of the exhaust leaks seems to have fixed my vacuum problem, the BOV not opens if i rev slightly to 1000 and let off throttle, which is wasn't before, and my brakes are back to being power brakes.

Will know if problem is truely solved ones we try tuning once again!

Hope you get your car working right Syritis

eoph

if adam told you to vent the stock bov to the atmosphere, that is another vac leak right there.

Syritis

iTrader: (2)

Adam didn't tell me to do anythign with my BOV, and yes they're is a one way valve past the BOV itself. so it doesn't pull from they're. I'm goign to get it running with what i KNOW works then, sometime I'll pull some money together for an actual BOV with the 60/1 turbo upgrade.

Today I fully charged my battary, and cranked over the engine with 75amp battary booster, and it started, sometimes it work upto 600rpm and stall. some time it would jsut stall, but if i moved the htrottle anywhere other then 1/4 throttle it would die instantly. I'm quite convinced that the cheap premix fould my plugs. cuz after a lot of crankign and no fire, it would spew lots of blue/purple smoke that didn't smell like gas or coolant, just smelt really bad. So i'm goign to top up my gas tank crank it over a bit to try and clear some premix from the lines, un flood from the chambers, then replace my spark plugs.

eoph

y didn't you just check to see if your plugs are fouled?

Syritis

iTrader: (2)

I did check them and they were getting good spark in my hand held against the housing, but tit didn't make much sense that my engine would run better with a battary booster, so i though back to the plugs and just replaced them and topped up the gas tank with some gas without adding pre-mix. My car will run, but if the rpms go under 1500 the car boggs and dies. so i'm back to the first problem but even the plugs helpped this problem a bit.
if i drown the brack booster area with some carb cleaner, i can get it to stumble once or twice not nearly enuff to cause a 3in.hg vacuum leak. The booster itself will hold a strong vacuum inside. none of the line look worn-out but i'll replace them anyways.
I did the quick check on the BAC valve again, and when u unplug the BAC the rpm is supost to drop a bit right, or is that only from idle. if the BAC valve was stuck open could that be causing my horrible vacuum reading, or even the bogging?

Syritis

iTrader: (2)

When the engine was out i replaced my p/s rack b/c it was leaking from both outter seals and when it was running my car would beep 5 times pause and repeat. an FAQ thread from dave say'd that it means they're something wrong with the P/S switch.
...Well.... according to the Mazda manual trouble shooting guide. The Clutch switch, neutral switch, and power steering switch control ur BAC system which controls ur idle, which controls my bogging problem.
so Hope fully I just gained a giant step in my predicament, so now i'm testing components that i would have never thought would be a cause of bogging.... yay....